Using Outlook for iOS for personal email and calendar management
If you only removed the Outlook email icon from your iPhone, your emails should not have been deleted.
Swipe left through your Home Screens until you reach the "App Library," search for Outlook, then press and hold the Outlook icon and choose "Add to Home Screen."
If Outlook is no longer installed, reinstall "Microsoft Outlook" from the App Store, then sign in with the same email account. Your emails should sync back.
If you mean the actual email messages were deleted, please let me know whether you can still see them in the "Deleted" folder or when you sign in at https://outlook.live.com
Click "Add comment" to let me know.
Thanks!